Imaging evaluation of the pregnant patient with suspected pulmonary embolism.

Pulmonary embolism is the leading cause of maternal death in the developed world. The clinical diagnosis of pulmonary embolism is particularly challenging in pregnant patients as physiologic changes of pregnancy can mimic symptoms of pulmonary embolism or deep venous thrombosis. Clinical decision and imaging algorithms for venous thromboembolic disease have been proposed in the literature for the general population, but have not undergone wide-scale validation in pregnant patients. Laboratory evaluation of D-dimer levels has likewise been established as a viable screening method in the general population but remains controversial in pregnant patients. Regardless of whether D-dimer levels are used in this population, the clinician must often rely on imaging tests to confirm or exclude a clinical suspicion of pulmonary embolism. Additional factors beyond test performance must be weighed during pregnancy: radiation exposure to the fetus and maternal breast tissue, the safety of intravenous contrast administration and the diagnostic accuracy of the various testing options so that diagnosis and proper management are not delayed. The epidemiology of pregnancy-related venous thromboembolic disease and the different diagnostic methods are reviewed, with emphasis on the pregnant patient. Finally, a diagnostic imaging algorithm is proposed for the evaluation of the pregnant patient when a clinical suspicion of pulmonary embolism exists.